What's your opinion on DM carriers - Page 1

Would you breed to a stud who is a carrier for DM, assuming he is titled and other health cleranaces are good? Basically, just assume this is a nice dog but he's a DM carrier. I realize there is a lot of differing opinion on this subject, but I'm curious to get a general idea of the majority. My opinion is no, there are many other dogs to breed to. Why choose one who is a carrier, but I also realize that throwing out the good dogs who are carriers just limits the gene pool even more. I guess its a double edged sword. 

Although it would remove a lot of nice producers from the gene pool, I do agree with you. If I was a breeder, I would not choose a DM carrier. To me it would be like breeding a dog with somewhat questionable hips, even when the dog is otherwise a "complete" package. Why choose to breed something, knowing that there is a good possibility of producing progeny that could develop DM? The test was created to be a tool for breeders, it seems to me a lot of people seem to be "dismissing" their dog's positive results because he/she is a "nice" dog. JMO. Not intended to offend anyone who may breed DM carriers. 

Such a shame and sham that people actually think a dog should be eliminated from breeding because of a DM carrier. It is not anything like questionable hips because it doesn't affect the dog's health, and if one believes in the DNA test, one can predict the outcome of a breeding if both parents are tested....not so easy with hips. Keep on with eliminating dogs from breeding through DNA, and what you'll end up with are DNA desirable dogs that aren't worth the powder to blow them away.

Joanro-

What do you mean it would not affect the dog' s health? If the dog is a DM carrier, doesn't that mean the dog is more susecptible to developing DM?

Also Joanro- I'm not challenging you, I am just curious :)

I thought you might believe that the dog's health would be affected if it was a "carrier". But no, supposedly the dog must have both alleles for DM for it to be "at risk" of developing the disease. But look, OFA will only recognize the first generation of nontested offspring from two "clear" parents, simply because it is a "mutation" in the DNA. So, you can eliminate every "at risk" or "carrier" from the gene pool, and you will never eliminate DM.

From the OFA website.

Understanding the DNA Test for Degenerative Myelopathy

We have discovered a mutation in a gene which is associated with development of degenerative myelopathy (DM). In that gene, the DNA occurs in two possible forms (or alleles). The “G” allele is the predominant form in dogs that seldom or never develop DM; you can think of it as the “Good” allele. The “A” allele is more frequent in dogs exhibiting clinical signs of DM; you can think of it as the “Affected” allele.

Summary: “A” allele is associated with DM; “G” allele is not associated with DM.

Since an individual dog inherits two alleles (one from the sire and one from the dam) there are three possible test results: two “A” alleles; one “A” and one “G” allele; and, two “G” alleles. Summary: Test results can be A/A (affected/at risk), A/G (carrier), or G/G (normal) .

Microscopic examination of a section of spinal cord (following euthanasia) is the "gold standard" for diagnosing and confirming DM. We do not have the opportunity to examine cord samples from all the dogs that have died or been euthanized due to DM, but for those cords submitted for evaluation, and where the cellular changes have been consistent with a diagnosis of DM, the dogs have had a DNA test result of A/A in all but 2 individuals. There is additional work being done to better understand these 2 exceptions, but it is clear that the vast majority of real DM cases do have the A/A test result.

Summary: Dogs that test A/G or G/G are very unlikely to develop DM. Dogs that test A/A are likely to develop clinical signs of DM at some point as they age. Additional research now in progress is focused on understanding why some A/A dogs show clincal signs of DM at 7 or 8 years of age while others only begin to show clinical signs at 14 or 15yrs or older, or may die from some other cause without developing recognized clinical signs of DM.

The “A” allele is very common in some breeds. In these breeds, an overly aggressive breeding program to eliminate the dogs testing A/A or A/G might be destructive to the breed as a whole because it would eliminate a large fraction of the high quality dogs that would otherwise contribute desirable qualities to the breed. Nonetheless, DM should be taken seriously. It is a fatal disease with devastating consequences for the dogs and a very unpleasant experience for the owners who care for them. Thus, a realistic approach when considering which dogs to select for breeding would be to consider dogs with the A/A or A/G test result to have a fault, just as a poor top-line or imperfect gait would be considered faults. Dogs that test A/A should be considered to have a worse fault than those that test A/G. Dog breeders could then continue to do what conscientious breeders have always done: make their selections for breeding stock in light of all of the dogs’ good points and all of the dogs’ faults. Using this approach over many generations should substantially reduce the prevalence of DM while continuing to maintain or improve those qualities that have contributed to the various dog breeds.

Summary: We recommend that dog breeders take into consideration the DM test results as they plan their breeding programs; however, they should not over-emphasize this test result. Instead, the test result is one factor among many in a balanced breeding program.

Personally I don't see anything wrong with using a breed worthy at risk with a clear.

Assuming the current DM DNA test is valid, a carrier cannot produce an at risk unless it's bred to an at risk or another carrier. It's assumed to be a simple recessive gene. I think the odds of an at risk GSD dying from DM is very low. No one knows why some at risks develop the disease while most don't....... The research continues.

The part I find SO MADDENING about the whole DM thing is the amount of sheer ingorance regarding it that prevails and scares people and leads to the further shallowing of the gene pool. The validity of the test is questionable at best. If you add "misunderstood" results on top of that, we could really end up in trouble. I personally have spoken to a stud dog owner who has a carrier male and a clear male, and the clear died of (supposed) DM. He was very involved in the early testing and now has come to the conclusion that it's bunk. I don't have enough information to decide either way. If someone wants me to test a dog, I certainly will, but no way am I going to refuse to breed a dog who is a carrier. We have enough problems trying to find "total package" dogs. I wholeheartedly agree with Joan and what a great way to put it as far as "perfect" DNA but that "aren't worth the powder to blow them away." Same thing as whether you'd rather have a super dog with fair hips or a mediocre dog with excellent hips. 

Hunterjumper, I felt compelled to disagree with your post hoping it would prompt people to look closer and see that your premise you were operating under in agreeing that DM carriers should NOT be used for breeding is utterly FALSE. You are certainly entitled to your opinion, however, the reason behind it turned out to be totally invalid, as you didn't understand what "carrier" meant. I'm using you as an example, not meaning to come down hard on you in particular. This happens all the time- ignorance leads to well-meaning ideals and opinions that end up being a  detriment to the breed as a whole. 

At this point, DM testing in gsds is a bunch of bunk.